Conventionally, for an insulated wire used in carrying out wiring of parts for a car and electric/electronic equipment, there is widespread use of an insulated wire in which a vinyl chloride resin composition to which a halogenous flame retardant is added is arranged to cover a conductor.
However, there is a problem that the insulated wire includes halogen elements, so that it emits harmful halogenous gas into the atmosphere in case of car fire or at the time of combustion for disposing of electric/electronic equipment by incineration, causing environmental pollution.
Therefore, from the view point of reducing loads on the global environment, a material for an insulator layer has been recently changed from the vinyl chloride resin composition to a polyolefin type resin composition which is prepared by adding a metallic hydrate such as a magnesium hydroxide to polyolefin such as polyethylene.
As an example of the polyolefin type resin composition, please refer to Japanese Patent Application Unexamined Publication No. Hei07-176219 which discloses an insulated wire including a composition as a material for an insulator layer, the composition containing 30 to 100 parts by weight of magnesium hydroxide with respect to 100 parts by weight of a blend polymer of straight-chain polyethylene and carboxylic acid denatured polyethylene.